1. Field of the Invention
The present invention relates to an ink jet cartridge having a recording head for recording by discharging ink from a discharging port integrated with a tank for storing ink which is supplied to the recording head, and an ink jet apparatus equipped with the cartridge.
2. Related Background Art
Recording means applicable to an ink jet apparatus may be mainly classified into a so-called serial-type head which scans a recording head in the direction perpendicular to a transporting direction of a recorded material and a so-called full line type head having discharging ports aligned within a width of a one-line portion of a recorded material which records by transporting the recorded material. The serial type head is further divided into a separate type having separately arranged recording head and ink tank for storing ink to be discharged, and a cartridge type which has a recording head and an ink tank integrated with each other so as to be exchangeably arranged in the ink jet apparatus.
Within a variety of these types of heads, the cartridge type is attracting attention as a preferable type of head suitable to a recording apparatus for personal use, since it can reduce initial cost, running cost, and the size and weight of the recording apparatus.
FIG. 6 shows an example of a typical structure of this type of head cartridge 20. In the example of FIG. 6, a porous absorber 21 is accommodated within an ink tank 21A in a compressed form and impregnated with ink.
On a lateral side of the ink tank 21 there is integrally mounted a recording head 22 having a discharging port 24 for discharging ink, and an ink supplying path 23 communicates the ink tank 21A with the recording head 22.
Supply of ink from the ink tank 21A to the recording head 22 is achieved by utilizing a pressure difference generated by pressing the ink supplying path 23 to the porous absorber 21 impregnated with ink. Specifically, this pressure difference allows ink to concentrate from the ink tank 21A to the supplying path 23, and the ink concentrated to that region is favorably introduced to the recording head 22 by utilizing a capillary action.
Although this type of ink jet head cartridge 20 achieves favorable ink discharge and provides a satisfactory recording quality, it further implies the following drawbacks to be improved which are caused by the characteristic of the ink tank 21A:
(1) A quantity of ink held by the porous absorber accommodated in the ink tank in a compressed form is approximately half of the volume of the ink tank; PA1 (2) Since the ink tank cannot store a large quantity of ink, the ink jet head cartridge must be exchanged many times; PA1 (3) The porous material is expensive; PA1 (4) Since the porous material is used, as the quantity of ink in the ink tank is decreased, a negative pressure on the absorber side becomes larger, which impedes smooth supply of ink to the head. It is therefore difficult to use up the ink to the last drop; PA1 (5) A further reduction in size of the cartridge is difficult. Specifically, if a smaller porous material is used, an ink storage quantity itself is also reduced; and PA1 (6) The size of the ink jet recording apparatus body cannot be further reduced due to the drawback (5).